Where are the best places to buy good quality kite shields these days? I have looked around online, but it looks like manufacturers are few and far between, unless there are some I am not aware of.

Yes, I've notices the same thing.

Mercenarie's Tailor used to provide a pretty good reasonably accurate product but I don't know who else is out there right now.

Over all, you are usually better of making them yourself, or buying a blank. Especially the strap placement is important when it comes to shield efficiency, and not all makers have extensive practical knowledge when it comes to this.

I usually make use of a staple gun to test strap configuarations before riveting them.

Kult of Athena did offer some nice ones, haven't looked recently though...

This one?
http://www.kultofathena.com/product.asp?item=...ite+Shield

Looks decent. I would rip of and rearrange the strapping, though. The angle is all wrong.
Fortunatley, the nails seem to be quite small so you can do this without damaging the shield.

I think that was one of them. Seems like they used to have a couple but now it looks like they are down to just this one.

Unless I am vastly mistaken that is the same shield found here:
http://www.battlemerchant.com/Schilde/Normann...:2390.html

In that case those aren't nails but rather screws so damaging the shield should be even less of an issue.

I can second that, it's not particularly strong. I've used mine in some pell work on a tree - mainly to not damage the tree but also to test the shield - and it holds up quite well to blows with a sword but when I went for broke and tried a Mordhau against it - even with out much force, basically dropping it against the shield - the guard went straight through. So not something I'd use for heavy duty combat

Shields are ammo. They break every once in a while. We use 6-8mm ply with cloth cover and rawhide edges for blunt steel fighting. Depending on the quality of the rawhide, they will last a couple of seasons of steady use (1-2 trainings a week). Unless you are actively trying to destroy them.
The alternative is making shields that are to heavy to use propperly, and end up gathering dust.

Making full force swings against people's shields with blunts is a common pursuit for showfighters and inexperienced reenactors. This time is better spent actually trying to score a kill, and in reallity would get your weapon stuck.